This invention relates to articles, and more particularly to electrodes suitable for use in electrolytic cells, at least partially composed of a catalytic, metal-containing, electrically conducting coordination polymer.
Electrodes for use in electrochemical cells must generally meet a combination of strict requirements with regard to conductivity, physical and chemical stability, corrosion resistance, manufacture and electrochemical performance, and more particularly, catalytic activity and selectivity.
Various efforts have been made to produce catalytic electrically conducting polymeric materials for use in articles such as electrodes. Incorporation of metals, metallic salts and metal complexes into polymers and resins to impart stability and/or conductivity is well known. These resins or polymers are used as a matrix for anchoring the redox center in a three-dimensional zone.
The state of the art with regard to electrocatalytic polymeric materials, and more specifically their use in electrodes, may be illustrated by the following examples. Tigner describes in U.S. Pat. No. 3,867,315 an electrode containing a resinous composition comprising nonconducting or semiconducting thermosetting resinous material wherein the matrix of the composition has dispersed therein a finely divided, copper metal-containing solid and a salt, said salt and copper metal-containing solid being present in amounts sufficient to render the composition electroconductive. U.S. Pat. Nos. 3,751,301 and 4,118,294 further describe other electrodes comprising powdered (or particulate) conductive material interspersed in a cured thermosetting resin. U.S. Pat. Nos. 4,287,032 and 4,402,906 and Great Britain Pat. No. 2,096,614A describe electrodes consisting of an electroconductive, electrocatalytic material finely dispersed in an insoluble semiconducting polymer network. Another type of electrode is described in U.S. Pat. No. 4,440,693 in which bis(diphenyl-glyoximate)Ni (II) complexes, which have planar structures and crystallize in stacks, are converted by oxidation with iodine into an electrically conductive compound bis-(diphenyl-glyoximate)-Ni. I.
Major problems associated with catalytic polymeric materials have been (1) loss of activity with time caused by the leaching of metal ions, and (2) inability to use thicker catalyst coatings due to increased electrical resistance.